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- // Copyright (c) 2012 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #include "base/files/file_path_watcher.h"
- #include <errno.h>
- #include <poll.h>
- #include <stddef.h>
- #include <string.h>
- #include <sys/inotify.h>
- #include <sys/ioctl.h>
- #include <sys/select.h>
- #include <unistd.h>
- #include <algorithm>
- #include <array>
- #include <fstream>
- #include <map>
- #include <memory>
- #include <set>
- #include <unordered_map>
- #include <utility>
- #include <vector>
- #include "base/bind.h"
- #include "base/containers/contains.h"
- #include "base/files/file_enumerator.h"
- #include "base/files/file_path.h"
- #include "base/files/file_path_watcher_inotify.h"
- #include "base/files/file_util.h"
- #include "base/lazy_instance.h"
- #include "base/location.h"
- #include "base/logging.h"
- #include "base/memory/ptr_util.h"
- #include "base/memory/scoped_refptr.h"
- #include "base/memory/weak_ptr.h"
- #include "base/posix/eintr_wrapper.h"
- #include "base/synchronization/lock.h"
- #include "base/task/single_thread_task_runner.h"
- #include "base/threading/platform_thread.h"
- #include "base/threading/scoped_blocking_call.h"
- #include "base/threading/sequenced_task_runner_handle.h"
- #include "base/trace_event/base_tracing.h"
- #include "build/build_config.h"
- namespace base {
- namespace {
- #if !BUILDFLAG(IS_FUCHSIA)
- // The /proc path to max_user_watches.
- constexpr char kInotifyMaxUserWatchesPath[] =
- "/proc/sys/fs/inotify/max_user_watches";
- // This is a soft limit. If there are more than |kExpectedFilePathWatches|
- // FilePathWatchers for a user, than they might affect each other's inotify
- // watchers limit.
- constexpr size_t kExpectedFilePathWatchers = 16u;
- // The default max inotify watchers limit per user, if reading
- // /proc/sys/fs/inotify/max_user_watches fails.
- constexpr size_t kDefaultInotifyMaxUserWatches = 8192u;
- #endif // !BUILDFLAG(IS_FUCHSIA)
- class FilePathWatcherImpl;
- class InotifyReader;
- // Used by test to override inotify watcher limit.
- size_t g_override_max_inotify_watches = 0u;
- // Get the maximum number of inotify watches can be used by a FilePathWatcher
- // instance. This is based on /proc/sys/fs/inotify/max_user_watches entry.
- size_t GetMaxNumberOfInotifyWatches() {
- #if BUILDFLAG(IS_FUCHSIA)
- // Fuchsia has no limit on the number of watches.
- return std::numeric_limits<int>::max();
- #else
- static const size_t max = []() {
- size_t max_number_of_inotify_watches = 0u;
- std::ifstream in(kInotifyMaxUserWatchesPath);
- if (!in.is_open() || !(in >> max_number_of_inotify_watches)) {
- LOG(ERROR) << "Failed to read " << kInotifyMaxUserWatchesPath;
- return kDefaultInotifyMaxUserWatches / kExpectedFilePathWatchers;
- }
- return max_number_of_inotify_watches / kExpectedFilePathWatchers;
- }();
- return g_override_max_inotify_watches ? g_override_max_inotify_watches : max;
- #endif // if BUILDFLAG(IS_FUCHSIA)
- }
- class InotifyReaderThreadDelegate final : public PlatformThread::Delegate {
- public:
- explicit InotifyReaderThreadDelegate(int inotify_fd)
- : inotify_fd_(inotify_fd) {}
- InotifyReaderThreadDelegate(const InotifyReaderThreadDelegate&) = delete;
- InotifyReaderThreadDelegate& operator=(const InotifyReaderThreadDelegate&) =
- delete;
- ~InotifyReaderThreadDelegate() override = default;
- private:
- void ThreadMain() override;
- const int inotify_fd_;
- };
- // Singleton to manage all inotify watches.
- // TODO(tony): It would be nice if this wasn't a singleton.
- // http://crbug.com/38174
- class InotifyReader {
- public:
- // Watch descriptor used by AddWatch() and RemoveWatch().
- #if BUILDFLAG(IS_ANDROID)
- using Watch = uint32_t;
- #else
- using Watch = int;
- #endif
- static constexpr Watch kInvalidWatch = static_cast<Watch>(-1);
- static constexpr Watch kWatchLimitExceeded = static_cast<Watch>(-2);
- InotifyReader(const InotifyReader&) = delete;
- InotifyReader& operator=(const InotifyReader&) = delete;
- // Watch directory |path| for changes. |watcher| will be notified on each
- // change. Returns |kInvalidWatch| on failure.
- Watch AddWatch(const FilePath& path, FilePathWatcherImpl* watcher);
- // Remove |watch| if it's valid.
- void RemoveWatch(Watch watch, FilePathWatcherImpl* watcher);
- // Invoked on "inotify_reader" thread to notify relevant watchers.
- void OnInotifyEvent(const inotify_event* event);
- // Returns true if any paths are actively being watched.
- bool HasWatches();
- private:
- friend struct LazyInstanceTraitsBase<InotifyReader>;
- // Record of watchers tracked for watch descriptors.
- struct WatcherEntry {
- scoped_refptr<SequencedTaskRunner> task_runner;
- WeakPtr<FilePathWatcherImpl> watcher;
- };
- InotifyReader();
- // There is no destructor because |g_inotify_reader| is a
- // base::LazyInstace::Leaky object. Having a destructor causes build
- // issues with GCC 6 (http://crbug.com/636346).
- // Returns true on successful thread creation.
- bool StartThread();
- Lock lock_;
- // Tracks which FilePathWatcherImpls to be notified on which watches.
- // The tracked FilePathWatcherImpl is keyed by raw pointers for fast look up
- // and mapped to a WatchEntry that is used to safely post a notification.
- std::unordered_map<Watch, std::map<FilePathWatcherImpl*, WatcherEntry>>
- watchers_ GUARDED_BY(lock_);
- // File descriptor returned by inotify_init.
- const int inotify_fd_;
- // Thread delegate for the Inotify thread.
- InotifyReaderThreadDelegate thread_delegate_;
- // Flag set to true when startup was successful.
- bool valid_ = false;
- };
- class FilePathWatcherImpl : public FilePathWatcher::PlatformDelegate {
- public:
- FilePathWatcherImpl();
- FilePathWatcherImpl(const FilePathWatcherImpl&) = delete;
- FilePathWatcherImpl& operator=(const FilePathWatcherImpl&) = delete;
- ~FilePathWatcherImpl() override;
- // Called for each event coming from the watch on the original thread.
- // |fired_watch| identifies the watch that fired, |child| indicates what has
- // changed, and is relative to the currently watched path for |fired_watch|.
- //
- // |created| is true if the object appears.
- // |deleted| is true if the object disappears.
- // |is_dir| is true if the object is a directory.
- void OnFilePathChanged(InotifyReader::Watch fired_watch,
- const FilePath::StringType& child,
- bool created,
- bool deleted,
- bool is_dir);
- // Returns whether the number of inotify watches of this FilePathWatcherImpl
- // would exceed the limit if adding one more.
- bool WouldExceedWatchLimit() const;
- // Returns the task runner to be used with this.
- scoped_refptr<SequencedTaskRunner> GetTaskRunner() const;
- // Returns the WeakPtr of this, must be called on the original sequence.
- WeakPtr<FilePathWatcherImpl> GetWeakPtr() const;
- private:
- // Start watching |path| for changes and notify |delegate| on each change.
- // Returns true if watch for |path| has been added successfully.
- bool Watch(const FilePath& path,
- Type type,
- const FilePathWatcher::Callback& callback) override;
- // Cancel the watch. This unregisters the instance with InotifyReader.
- void Cancel() override;
- // Inotify watches are installed for all directory components of |target_|.
- // A WatchEntry instance holds:
- // - |watch|: the watch descriptor for a component.
- // - |subdir|: the subdirectory that identifies the next component.
- // - For the last component, there is no next component, so it is empty.
- // - |linkname|: the target of the symlink.
- // - Only if the target being watched is a symbolic link.
- struct WatchEntry {
- explicit WatchEntry(const FilePath::StringType& dirname)
- : watch(InotifyReader::kInvalidWatch), subdir(dirname) {}
- InotifyReader::Watch watch;
- FilePath::StringType subdir;
- FilePath::StringType linkname;
- };
- // Reconfigure to watch for the most specific parent directory of |target_|
- // that exists. Also calls UpdateRecursiveWatches() below. Returns true if
- // watch limit is not hit. Otherwise, returns false.
- [[nodiscard]] bool UpdateWatches();
- // Reconfigure to recursively watch |target_| and all its sub-directories.
- // - This is a no-op if the watch is not recursive.
- // - If |target_| does not exist, then clear all the recursive watches.
- // - Assuming |target_| exists, passing kInvalidWatch as |fired_watch| forces
- // addition of recursive watches for |target_|.
- // - Otherwise, only the directory associated with |fired_watch| and its
- // sub-directories will be reconfigured.
- // Returns true if watch limit is not hit. Otherwise, returns false.
- [[nodiscard]] bool UpdateRecursiveWatches(InotifyReader::Watch fired_watch,
- bool is_dir);
- // Enumerate recursively through |path| and add / update watches.
- // Returns true if watch limit is not hit. Otherwise, returns false.
- [[nodiscard]] bool UpdateRecursiveWatchesForPath(const FilePath& path);
- // Do internal bookkeeping to update mappings between |watch| and its
- // associated full path |path|.
- void TrackWatchForRecursion(InotifyReader::Watch watch, const FilePath& path);
- // Remove all the recursive watches.
- void RemoveRecursiveWatches();
- // |path| is a symlink to a non-existent target. Attempt to add a watch to
- // the link target's parent directory. Update |watch_entry| on success.
- // Returns true if watch limit is not hit. Otherwise, returns false.
- [[nodiscard]] bool AddWatchForBrokenSymlink(const FilePath& path,
- WatchEntry* watch_entry);
- bool HasValidWatchVector() const;
- // Callback to notify upon changes.
- FilePathWatcher::Callback callback_;
- // The file or directory we're supposed to watch.
- FilePath target_;
- Type type_ = Type::kNonRecursive;
- // The vector of watches and next component names for all path components,
- // starting at the root directory. The last entry corresponds to the watch for
- // |target_| and always stores an empty next component name in |subdir|.
- std::vector<WatchEntry> watches_;
- std::unordered_map<InotifyReader::Watch, FilePath> recursive_paths_by_watch_;
- std::map<FilePath, InotifyReader::Watch> recursive_watches_by_path_;
- WeakPtrFactory<FilePathWatcherImpl> weak_factory_{this};
- };
- LazyInstance<InotifyReader>::Leaky g_inotify_reader = LAZY_INSTANCE_INITIALIZER;
- void InotifyReaderThreadDelegate::ThreadMain() {
- PlatformThread::SetName("inotify_reader");
- std::array<pollfd, 1> fdarray{{{inotify_fd_, POLLIN, 0}}};
- while (true) {
- // Wait until some inotify events are available.
- int poll_result = HANDLE_EINTR(poll(fdarray.data(), fdarray.size(), -1));
- if (poll_result < 0) {
- DPLOG(WARNING) << "poll failed";
- return;
- }
- // Adjust buffer size to current event queue size.
- int buffer_size;
- int ioctl_result = HANDLE_EINTR(ioctl(inotify_fd_, FIONREAD, &buffer_size));
- if (ioctl_result != 0 || buffer_size < 0) {
- DPLOG(WARNING) << "ioctl failed";
- return;
- }
- std::vector<char> buffer(static_cast<size_t>(buffer_size));
- ssize_t bytes_read = HANDLE_EINTR(
- read(inotify_fd_, buffer.data(), static_cast<size_t>(buffer_size)));
- if (bytes_read < 0) {
- DPLOG(WARNING) << "read from inotify fd failed";
- return;
- }
- for (size_t i = 0; i < static_cast<size_t>(bytes_read);) {
- inotify_event* event = reinterpret_cast<inotify_event*>(&buffer[i]);
- size_t event_size = sizeof(inotify_event) + event->len;
- DCHECK(i + event_size <= static_cast<size_t>(bytes_read));
- g_inotify_reader.Get().OnInotifyEvent(event);
- i += event_size;
- }
- }
- }
- InotifyReader::InotifyReader()
- : inotify_fd_(inotify_init()), thread_delegate_(inotify_fd_) {
- if (inotify_fd_ < 0) {
- PLOG(ERROR) << "inotify_init() failed";
- return;
- }
- if (!StartThread())
- return;
- valid_ = true;
- }
- bool InotifyReader::StartThread() {
- // This object is LazyInstance::Leaky, so thread_delegate_ will outlive the
- // thread.
- return PlatformThread::CreateNonJoinable(0, &thread_delegate_);
- }
- InotifyReader::Watch InotifyReader::AddWatch(const FilePath& path,
- FilePathWatcherImpl* watcher) {
- if (!valid_)
- return kInvalidWatch;
- if (watcher->WouldExceedWatchLimit())
- return kWatchLimitExceeded;
- AutoLock auto_lock(lock_);
- ScopedBlockingCall scoped_blocking_call(FROM_HERE, BlockingType::WILL_BLOCK);
- const int watch_int =
- inotify_add_watch(inotify_fd_, path.value().c_str(),
- IN_ATTRIB | IN_CREATE | IN_DELETE | IN_CLOSE_WRITE |
- IN_MOVE | IN_ONLYDIR);
- if (watch_int == -1)
- return kInvalidWatch;
- const Watch watch = static_cast<Watch>(watch_int);
- watchers_[watch].emplace(std::make_pair(
- watcher, WatcherEntry{watcher->GetTaskRunner(), watcher->GetWeakPtr()}));
- return watch;
- }
- void InotifyReader::RemoveWatch(Watch watch, FilePathWatcherImpl* watcher) {
- if (!valid_ || (watch == kInvalidWatch))
- return;
- AutoLock auto_lock(lock_);
- auto watchers_it = watchers_.find(watch);
- if (watchers_it == watchers_.end())
- return;
- auto& watcher_map = watchers_it->second;
- watcher_map.erase(watcher);
- if (watcher_map.empty()) {
- watchers_.erase(watchers_it);
- ScopedBlockingCall scoped_blocking_call(FROM_HERE,
- BlockingType::WILL_BLOCK);
- inotify_rm_watch(inotify_fd_, watch);
- }
- }
- void InotifyReader::OnInotifyEvent(const inotify_event* event) {
- if (event->mask & IN_IGNORED)
- return;
- FilePath::StringType child(event->len ? event->name : FILE_PATH_LITERAL(""));
- AutoLock auto_lock(lock_);
- // In racing conditions, RemoveWatch() could grab `lock_` first and remove
- // the entry for `event->wd`.
- auto watchers_it = watchers_.find(static_cast<Watch>(event->wd));
- if (watchers_it == watchers_.end())
- return;
- auto& watcher_map = watchers_it->second;
- for (const auto& entry : watcher_map) {
- auto& watcher_entry = entry.second;
- watcher_entry.task_runner->PostTask(
- FROM_HERE,
- BindOnce(&FilePathWatcherImpl::OnFilePathChanged, watcher_entry.watcher,
- static_cast<Watch>(event->wd), child,
- event->mask & (IN_CREATE | IN_MOVED_TO),
- event->mask & (IN_DELETE | IN_MOVED_FROM),
- event->mask & IN_ISDIR));
- }
- }
- bool InotifyReader::HasWatches() {
- AutoLock auto_lock(lock_);
- return !watchers_.empty();
- }
- FilePathWatcherImpl::FilePathWatcherImpl() = default;
- FilePathWatcherImpl::~FilePathWatcherImpl() {
- DCHECK(!task_runner() || task_runner()->RunsTasksInCurrentSequence());
- }
- void FilePathWatcherImpl::OnFilePathChanged(InotifyReader::Watch fired_watch,
- const FilePath::StringType& child,
- bool created,
- bool deleted,
- bool is_dir) {
- DCHECK(task_runner()->RunsTasksInCurrentSequence());
- DCHECK(!watches_.empty());
- DCHECK(HasValidWatchVector());
- // Used below to avoid multiple recursive updates.
- bool did_update = false;
- // Whether kWatchLimitExceeded is encountered during update.
- bool exceeded_limit = false;
- // Find the entries in |watches_| that correspond to |fired_watch|.
- for (size_t i = 0; i < watches_.size(); ++i) {
- const WatchEntry& watch_entry = watches_[i];
- if (fired_watch != watch_entry.watch)
- continue;
- // Check whether a path component of |target_| changed.
- bool change_on_target_path = child.empty() ||
- (child == watch_entry.linkname) ||
- (child == watch_entry.subdir);
- // Check if the change references |target_| or a direct child of |target_|.
- bool target_changed;
- if (watch_entry.subdir.empty()) {
- // The fired watch is for a WatchEntry without a subdir. Thus for a given
- // |target_| = "/path/to/foo", this is for "foo". Here, check either:
- // - the target has no symlink: it is the target and it changed.
- // - the target has a symlink, and it matches |child|.
- target_changed =
- (watch_entry.linkname.empty() || child == watch_entry.linkname);
- } else {
- // The fired watch is for a WatchEntry with a subdir. Thus for a given
- // |target_| = "/path/to/foo", this is for {"/", "/path", "/path/to"}.
- // So we can safely access the next WatchEntry since we have not reached
- // the end yet. Check |watch_entry| is for "/path/to", i.e. the next
- // element is "foo".
- bool next_watch_may_be_for_target = watches_[i + 1].subdir.empty();
- if (next_watch_may_be_for_target) {
- // The current |watch_entry| is for "/path/to", so check if the |child|
- // that changed is "foo".
- target_changed = watch_entry.subdir == child;
- } else {
- // The current |watch_entry| is not for "/path/to", so the next entry
- // cannot be "foo". Thus |target_| has not changed.
- target_changed = false;
- }
- }
- // Update watches if a directory component of the |target_| path
- // (dis)appears. Note that we don't add the additional restriction of
- // checking the event mask to see if it is for a directory here as changes
- // to symlinks on the target path will not have IN_ISDIR set in the event
- // masks. As a result we may sometimes call UpdateWatches() unnecessarily.
- if (change_on_target_path && (created || deleted) && !did_update) {
- if (!UpdateWatches()) {
- exceeded_limit = true;
- break;
- }
- did_update = true;
- }
- // Report the following events:
- // - The target or a direct child of the target got changed (in case the
- // watched path refers to a directory).
- // - One of the parent directories got moved or deleted, since the target
- // disappears in this case.
- // - One of the parent directories appears. The event corresponding to
- // the target appearing might have been missed in this case, so recheck.
- if (target_changed || (change_on_target_path && deleted) ||
- (change_on_target_path && created && PathExists(target_))) {
- if (!did_update) {
- if (!UpdateRecursiveWatches(fired_watch, is_dir)) {
- exceeded_limit = true;
- break;
- }
- did_update = true;
- }
- callback_.Run(target_, /*error=*/false); // `this` may be deleted.
- return;
- }
- }
- if (!exceeded_limit && Contains(recursive_paths_by_watch_, fired_watch)) {
- if (!did_update) {
- if (!UpdateRecursiveWatches(fired_watch, is_dir))
- exceeded_limit = true;
- }
- if (!exceeded_limit) {
- callback_.Run(target_, /*error=*/false); // `this` may be deleted.
- return;
- }
- }
- if (exceeded_limit) {
- // Cancels all in-flight events from inotify thread.
- weak_factory_.InvalidateWeakPtrs();
- // Reset states and cancels all watches.
- auto callback = callback_;
- Cancel();
- // Fires the "error=true" callback.
- callback.Run(target_, /*error=*/true); // `this` may be deleted.
- }
- }
- bool FilePathWatcherImpl::WouldExceedWatchLimit() const {
- DCHECK(task_runner()->RunsTasksInCurrentSequence());
- // `watches_` contains inotify watches of all dir components of `target_`.
- // `recursive_paths_by_watch_` contains inotify watches for sub dirs under
- // `target_` of a Type::kRecursive watcher and keyed by inotify watches.
- // All inotify watches used by this FilePathWatcherImpl are either in
- // `watches_` or as a key in `recursive_paths_by_watch_`. As a result, the
- // two provide a good estimate on the number of inofiy watches used by this
- // FilePathWatcherImpl.
- const size_t number_of_inotify_watches =
- watches_.size() + recursive_paths_by_watch_.size();
- return number_of_inotify_watches >= GetMaxNumberOfInotifyWatches();
- }
- scoped_refptr<SequencedTaskRunner> FilePathWatcherImpl::GetTaskRunner() const {
- DCHECK(task_runner()->RunsTasksInCurrentSequence());
- return task_runner();
- }
- WeakPtr<FilePathWatcherImpl> FilePathWatcherImpl::GetWeakPtr() const {
- DCHECK(task_runner()->RunsTasksInCurrentSequence());
- return weak_factory_.GetWeakPtr();
- }
- bool FilePathWatcherImpl::Watch(const FilePath& path,
- Type type,
- const FilePathWatcher::Callback& callback) {
- DCHECK(target_.empty());
- set_task_runner(SequencedTaskRunnerHandle::Get());
- callback_ = callback;
- target_ = path;
- type_ = type;
- std::vector<FilePath::StringType> comps = target_.GetComponents();
- DCHECK(!comps.empty());
- for (size_t i = 1; i < comps.size(); ++i)
- watches_.emplace_back(comps[i]);
- watches_.emplace_back(FilePath::StringType());
- if (!UpdateWatches()) {
- Cancel();
- // Note `callback` is not invoked since false is returned.
- return false;
- }
- return true;
- }
- void FilePathWatcherImpl::Cancel() {
- if (!callback_) {
- // Watch() was never called.
- set_cancelled();
- return;
- }
- DCHECK(task_runner()->RunsTasksInCurrentSequence());
- DCHECK(!is_cancelled());
- set_cancelled();
- callback_.Reset();
- for (const auto& watch : watches_)
- g_inotify_reader.Get().RemoveWatch(watch.watch, this);
- watches_.clear();
- target_.clear();
- RemoveRecursiveWatches();
- }
- bool FilePathWatcherImpl::UpdateWatches() {
- // Ensure this runs on the task_runner() exclusively in order to avoid
- // concurrency issues.
- DCHECK(task_runner()->RunsTasksInCurrentSequence());
- DCHECK(HasValidWatchVector());
- // Walk the list of watches and update them as we go.
- FilePath path(FILE_PATH_LITERAL("/"));
- for (WatchEntry& watch_entry : watches_) {
- InotifyReader::Watch old_watch = watch_entry.watch;
- watch_entry.watch = InotifyReader::kInvalidWatch;
- watch_entry.linkname.clear();
- watch_entry.watch = g_inotify_reader.Get().AddWatch(path, this);
- if (watch_entry.watch == InotifyReader::kWatchLimitExceeded)
- return false;
- if (watch_entry.watch == InotifyReader::kInvalidWatch) {
- // Ignore the error code (beyond symlink handling) to attempt to add
- // watches on accessible children of unreadable directories. Note that
- // this is a best-effort attempt; we may not catch events in this
- // scenario.
- if (IsLink(path)) {
- if (!AddWatchForBrokenSymlink(path, &watch_entry))
- return false;
- }
- }
- if (old_watch != watch_entry.watch)
- g_inotify_reader.Get().RemoveWatch(old_watch, this);
- path = path.Append(watch_entry.subdir);
- }
- return UpdateRecursiveWatches(InotifyReader::kInvalidWatch, /*is_dir=*/false);
- }
- bool FilePathWatcherImpl::UpdateRecursiveWatches(
- InotifyReader::Watch fired_watch,
- bool is_dir) {
- DCHECK(HasValidWatchVector());
- if (type_ != Type::kRecursive)
- return true;
- if (!DirectoryExists(target_)) {
- RemoveRecursiveWatches();
- return true;
- }
- // Check to see if this is a forced update or if some component of |target_|
- // has changed. For these cases, redo the watches for |target_| and below.
- if (!Contains(recursive_paths_by_watch_, fired_watch) &&
- fired_watch != watches_.back().watch) {
- return UpdateRecursiveWatchesForPath(target_);
- }
- // Underneath |target_|, only directory changes trigger watch updates.
- if (!is_dir)
- return true;
- const FilePath& changed_dir = Contains(recursive_paths_by_watch_, fired_watch)
- ? recursive_paths_by_watch_[fired_watch]
- : target_;
- auto start_it = recursive_watches_by_path_.upper_bound(changed_dir);
- auto end_it = start_it;
- for (; end_it != recursive_watches_by_path_.end(); ++end_it) {
- const FilePath& cur_path = end_it->first;
- if (!changed_dir.IsParent(cur_path))
- break;
- // There could be a race when another process is changing contents under
- // `changed_dir` while chrome is watching (e.g. an Android app updating
- // a dir with Chrome OS file manager open for the dir). In such case,
- // `cur_dir` under `changed_dir` could exist in this loop but not in
- // the FileEnumerator loop in the upcoming UpdateRecursiveWatchesForPath(),
- // As a result, `g_inotify_reader` would have an entry in its `watchers_`
- // pointing to `this` but `this` is no longer aware of that. Crash in
- // http://crbug/990004 could happen later.
- //
- // Remove the watcher of `cur_path` regardless of whether it exists
- // or not to keep `this` and `g_inotify_reader` consistent even when the
- // race happens. The watcher will be added back if `cur_path` exists in
- // the FileEnumerator loop in UpdateRecursiveWatchesForPath().
- g_inotify_reader.Get().RemoveWatch(end_it->second, this);
- // Keep it in sync with |recursive_watches_by_path_| crbug.com/995196.
- recursive_paths_by_watch_.erase(end_it->second);
- }
- recursive_watches_by_path_.erase(start_it, end_it);
- return UpdateRecursiveWatchesForPath(changed_dir);
- }
- bool FilePathWatcherImpl::UpdateRecursiveWatchesForPath(const FilePath& path) {
- DCHECK_EQ(type_, Type::kRecursive);
- DCHECK(!path.empty());
- DCHECK(DirectoryExists(path));
- // Note: SHOW_SYM_LINKS exposes symlinks as symlinks, so they are ignored
- // rather than followed. Following symlinks can easily lead to the undesirable
- // situation where the entire file system is being watched.
- FileEnumerator enumerator(
- path, true /* recursive enumeration */,
- FileEnumerator::DIRECTORIES | FileEnumerator::SHOW_SYM_LINKS);
- for (FilePath current = enumerator.Next(); !current.empty();
- current = enumerator.Next()) {
- DCHECK(enumerator.GetInfo().IsDirectory());
- if (!Contains(recursive_watches_by_path_, current)) {
- // Add new watches.
- InotifyReader::Watch watch =
- g_inotify_reader.Get().AddWatch(current, this);
- if (watch == InotifyReader::kWatchLimitExceeded)
- return false;
- TrackWatchForRecursion(watch, current);
- } else {
- // Update existing watches.
- InotifyReader::Watch old_watch = recursive_watches_by_path_[current];
- DCHECK_NE(InotifyReader::kInvalidWatch, old_watch);
- InotifyReader::Watch watch =
- g_inotify_reader.Get().AddWatch(current, this);
- if (watch == InotifyReader::kWatchLimitExceeded)
- return false;
- if (watch != old_watch) {
- g_inotify_reader.Get().RemoveWatch(old_watch, this);
- recursive_paths_by_watch_.erase(old_watch);
- recursive_watches_by_path_.erase(current);
- TrackWatchForRecursion(watch, current);
- }
- }
- }
- return true;
- }
- void FilePathWatcherImpl::TrackWatchForRecursion(InotifyReader::Watch watch,
- const FilePath& path) {
- DCHECK_EQ(type_, Type::kRecursive);
- DCHECK(!path.empty());
- DCHECK(target_.IsParent(path));
- if (watch == InotifyReader::kInvalidWatch)
- return;
- DCHECK(!Contains(recursive_paths_by_watch_, watch));
- DCHECK(!Contains(recursive_watches_by_path_, path));
- recursive_paths_by_watch_[watch] = path;
- recursive_watches_by_path_[path] = watch;
- }
- void FilePathWatcherImpl::RemoveRecursiveWatches() {
- if (type_ != Type::kRecursive)
- return;
- for (const auto& it : recursive_paths_by_watch_)
- g_inotify_reader.Get().RemoveWatch(it.first, this);
- recursive_paths_by_watch_.clear();
- recursive_watches_by_path_.clear();
- }
- bool FilePathWatcherImpl::AddWatchForBrokenSymlink(const FilePath& path,
- WatchEntry* watch_entry) {
- #if BUILDFLAG(IS_FUCHSIA)
- // Fuchsia does not support symbolic links.
- return false;
- #else // BUILDFLAG(IS_FUCHSIA)
- DCHECK_EQ(InotifyReader::kInvalidWatch, watch_entry->watch);
- FilePath link;
- if (!ReadSymbolicLink(path, &link))
- return true;
- if (!link.IsAbsolute())
- link = path.DirName().Append(link);
- // Try watching symlink target directory. If the link target is "/", then we
- // shouldn't get here in normal situations and if we do, we'd watch "/" for
- // changes to a component "/" which is harmless so no special treatment of
- // this case is required.
- InotifyReader::Watch watch =
- g_inotify_reader.Get().AddWatch(link.DirName(), this);
- if (watch == InotifyReader::kWatchLimitExceeded)
- return false;
- if (watch == InotifyReader::kInvalidWatch) {
- // TODO(craig) Symlinks only work if the parent directory for the target
- // exist. Ideally we should make sure we've watched all the components of
- // the symlink path for changes. See crbug.com/91561 for details.
- DPLOG(WARNING) << "Watch failed for " << link.DirName().value();
- return true;
- }
- watch_entry->watch = watch;
- watch_entry->linkname = link.BaseName().value();
- return true;
- #endif // BUILDFLAG(IS_FUCHSIA)
- }
- bool FilePathWatcherImpl::HasValidWatchVector() const {
- if (watches_.empty())
- return false;
- for (size_t i = 0; i < watches_.size() - 1; ++i) {
- if (watches_[i].subdir.empty())
- return false;
- }
- return watches_.back().subdir.empty();
- }
- } // namespace
- ScopedMaxNumberOfInotifyWatchesOverrideForTest::
- ScopedMaxNumberOfInotifyWatchesOverrideForTest(size_t override_max) {
- DCHECK_EQ(g_override_max_inotify_watches, 0u);
- g_override_max_inotify_watches = override_max;
- }
- ScopedMaxNumberOfInotifyWatchesOverrideForTest::
- ~ScopedMaxNumberOfInotifyWatchesOverrideForTest() {
- g_override_max_inotify_watches = 0u;
- }
- FilePathWatcher::FilePathWatcher() {
- sequence_checker_.DetachFromSequence();
- impl_ = std::make_unique<FilePathWatcherImpl>();
- }
- #if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS)
- // Put inside "BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS)" because Android
- // includes file_path_watcher_linux.cc.
- // static
- bool FilePathWatcher::HasWatchesForTest() {
- return g_inotify_reader.Get().HasWatches();
- }
- #endif // BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS)
- } // namespace base
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